To protect and stabilize components contained within a housing, it is known to fill the housing with a flowable material, such as epoxy. The flowable material surrounds the components and subsequently hardens in place around the components, holding the components within the matrix formed by the flowable material within the housing. This practice, commonly referred to as “potting,” is used in a wide variety of applications. A fuel pump will be used as one example in the following discussion. However, it should be understood that the discussion is applicable to a much wider range of applications. Fuel pumps are subject to a number of environmental stresses, such as vibration, shock, and exposure to aggressive chemicals, such as petroleum-based compounds or salt solutions. To protect relatively delicate components, such as electronic circuitry, contained within a pump housing from the aforementioned environmental stresses, it is know to pot a pump housing.
Power and control circuitry in a fuel pump, for example, an oscillating circuit, produce heat, which must be removed to protect the circuitry. If the circuitry is not adequately cooled, circuit components can suffer heat-induced damage, the operation of the circuitry may be compromised, and the operating life of the circuitry can be dramatically shortened. Certain modes of operation for a fuel pump, for example, running the pump “dry,” that is, running the pump when there is no fuel in the associated fuel tank and thus no fuel flowing through the pump, increase the ambient temperature of the housing. In dry run conditions, failure of circuitry due to thermal overload occurs much more quickly than under normal operation conditions.
In general, heat can be transferred from circuitry by convection, for example, by air passing over the circuitry, by radiation, or by conduction. Unfortunately, potting materials prevent heat transfer by radiation and convection. Thus, for a potted fuel pump, conduction is the only means of heat transfer available for components within the fuel pump housing. Thus, to conduct sufficient heat away from circuitry in a potted fuel pump, a heat sink must have adequate capacity and a tight conductive connection between the circuitry and the heat sink. Known fuel pumps suffer from a lack of sufficient heat sinking capability and/or fail to maintain the required conductive contact between the circuitry and the heat sinking capacity available in the pump.
Thus, there has been a longfelt need for a heat sink assembly to adequately conduct heat away from components in a potted housing, particularly under adverse conditions, such a dry pumping.